Method of manufacturing disintegrated bronze foils



Oct. 31, 1933. E, RA R 1,932,741

METHOD OF MANUFACTURING DISINTEGRATED BRONZE FOILS Filed May 12, 1931 2 Sheets-Sheet 1 \g. Sfah/kugg/ 60w Qammr E. KRAMER Oct. 31, 1933.

METHOD OF MANUFACTURING DISINTEGRATED BRONZE FOILS Filed May 12, 1931 2 Sheets-Sheet 2 T Q Q w c m 0 Q w m 8 0 m w QN m W9 mv vN w Patented 31, 1933 PATENT OFFICE us'rnon or MANUFACTURING msmmomma aaonzs FOILS I Erwin Kramer, Berlin, Germany, asaignor to firm Hartstofl-Metall A. G.,- Berlin-Copenlck,

Germany appumioa May 12, 1931, Serial No. 536,789,

and in Germany Imam-(01.334)

This invention relates to an improved method for the manufacture of disintegrated bronze ioils, so-called bronze colors, as well as to an improved device for manufacturing such colors I with the aid 0! steel balls provided within a rotating drum that contains also the metal particles to be spread out, the balls being lifted by the drum when it rotates and being dropped upon the metallic particles whereby the spreading-out is eifected.

The object ofthe invention is to increase considerably the eificiency of said method, and I attain the object in view by determining the amount of the steel balls according to, or within, certain limits.

Generally the manufacture of the bronze colors is carried out in this way that the most favorable efiiciency is determined by varying the degree of filling oi the drum with the particles. If that rule is applied to the-present case, the first result is that an increase of'the steel balls together with an increaseof the metal particles to be worked causes an increase of the amount of the finished particles. The output rises to a certain distinct maximum and becomes then lower it still more steel balls are introduced into the drum, and this reduction of the output increases with a further increase of the balls.

Although .it does, in view of this negative result, not seem advisable to increase the output by still another addition of balls, it is nevertheless a surprising fact that such a result is possible and that, in fact, the output can'be increased considerably, even above the beforementioned maximum. There exists a second maximum which is by far above the first, the increase residing not only in a greater output in proportion to the increase of the number of the balls, but also in an increased weight or thebronzeperkg.otsteelballs.

The invention is illustrated 1 u tically and by way of example on the accompanying drawingsonwhichFigure lisadiagramshowing the output in bronze in proportion to the weightofthesteelballs,Figure2ispartlyan axial section through, and partly a side-view of, a plant so designed that it works according to the improved method and Figure 3 is a cross section on the line AB of Figure 2. The diagrampertainstoadrumhavingaclearwidth of 600 mm. The ordinates show the output in kg. when aluminum particles are spread out; the abscissa: show the weight of the'steel balls inkg.permeterofthelengthofthedrum.

May 16, 1930 The diagram shows distinctly the increase of the output up to 102 kg. weight of the balls; then the output sinks quickly down to a weight of the balls of about 150 kg. and sinks further, but slowly, down to a ball weight of 198 kg. But from this point the curve rises quickly. The first maximum is attained at a ball weight of about 235 kg. of balls and finally the second maximum is attained at 290 kg. of balls, whereafter the curve sinks anew. I,

This peculiar phenomenon may be explained, perhaps, in this way that the falling balls in the present case do a particular kind of work, viz. the spreading-out of small metallic particles to disintegrated bronze foils or bronze particles, that particular kind of work being due to a certain distinct regulation of the fall of the balls,

a certain distinct sire of the same, and a certain distinct proportion between the weight of the balls, i. e. the amount thereof, and the amount of the metal particles to be worked.

Now, according to this invention, such amount of steel balls is introduced into the drum, in order to effect the spreading-out procedure, that the second rise of the curve which extends above the first maximum, but follows the minimum lying thereafter, is utilized for the specific output. According to the dimensions of the drum in which the method is carried out, also according to the size of the steel balls and the kind and condition of the metallic particles to be treated, the curve, i. e. its several portions. will run, of course, differently from that shown in Fig.1.

The diagram of Fig. 1 shows also that the second maximum of the curve falls quickly when the amount of the steel balls is still more increased. Therefore, from reasons of precaution the amount of the steel balls will be so determined that it corresponds not directly to the maximum but to a little therebelow so that with respect to the inaccuracies the strongly declined portion of the curve is not suddenly arrived at.

In the details the curve image can be determined, of course, with the aid of trials. Generi b, the principle can be stipulated that the amount of the steel balls when the drum is in its position of rest shall be such as to fill a segment of the circular sectional area of the drum, the height of the segmentamounting to more than two fifths of the radius of the circle. The upper limit which the height of the said 110 segment may have lies at about five sixths of said radius.

The high degree of filling of the drum with the balls produces also the favorable phenomenon that the point of gravity of the entire system lies comparatively near to the axis of rotation of thedrum, and that owing thereto the amount of power requisite for turning the drum is correspondingly slight.

Many metal particles, especially disintegrated waste portions of aluminium foil, possess a very great throwing-up volume when they are in unspread state. With the amounts of balls, as stated, it therefore occurs that the balls, together with the metal particles to be worked, fill up the entire space of the drum. In such a case the proper fall of the balls is, of course, strongly impeded and a pretty long period of time elapses until the balls have spread-out the metal particles to such an extent that their volume is in correspondence with the intended fall of the balls As regards the present case, a particular advantage resides therein that the filling of the drum and the emptying thereof pro,- ceeds, or is carried out, possibly'gradually and continually, as in this case the freshly sup plied metal particles that have not yet spread out constitute only a small percentage in proportion to the already worked. particles and are not able to cause disturbances.

The supply of the metal particles is, there.- fore, effected preferably by one of the known conveying devices, for instance a conveying worm, a rotary sluice or the like, whereas the discharge is effected with the aid of a current of air.

Figures 2 and 3 show a constructional form of a machine designed for carrying out the improved method. The plant is completely closed and all members are filled with aninert gas in order to prevent an explosion.

'I'he non-worked metal particles are contained in a store receptacle 1 and are conveyed from it to the tube 5 by means of a conveying worm located in the tube 3. From the tube '5 the particles pass into the drum 12 through one branch of a three-branch tube 9. The drum contains the steel balls 15. The drum is rotary and is turned by any suitable driving means. A current of air produced by the blower 6 enters through the tube 16, 17 also intothe tube 10 through the branch 17 of this tube, and streams through the drum 12 where it carries with it the suiliciently finely spread-out metallic particles which then are carried by that air through the tube or bend l3 and through a pipe 13 into the sifter 19 in which the metallic foils are sifted, the unfinished ones passing through a rotary sluice 23 into the branch 7 of the tube 10, from which they get back into the drum. The finished particles, however, pass through a tube 8 into a separating device, for instance a,

so-called cyclone, from which they get down to prevent der by subjecting metallic particlesto the falling action of balls in a rotary drum, the method of determining the proper proportions of the metallic particles and balls in order to obtain high efficiency inoutput of the powder which consists in placing a quantity ofballs inthe drum, supplying metallic particles'to the drum until the output of the metallicpowder rises-to a distinct maximum, and then supplying more balls until the output of the powder falls.- to a minimum and subsequently rises toa second maximum higher than the first maximum.

ERWIN KRAMER. I 

